Bobbin assembly for relay

ABSTRACT

A bobbin assembly in an electric relay, the bobbin having a pair of flanges and with one of the flanges having an associated cap which at least partially encloses the end of the bobbin and which serves as a seating surface for an iron core, the cap having windows formed therein to provide access for a staking tool so that the core is held captive within the bobbin prior to assembly in the relay. The outer end of the core carries a shading ring which is held in registered position by an embossment. The cap is clamped between the core and the frame of the relay to provide a magnetic gap thereby to reduce the level of residual flux when the relay coil is de-energized.

I United States Patent 1 Garbark BOBBIN ASSEMBLY FOR RELAY V [75]Inventor: Roman F. Garbark, Northlake, Ill.

[73] Assignee: D. Gottieb & Company, Chicago,

Ill.

[22] Filed: Aug. 21, 1972 [21] Appl. No: 282,312

[52] US. Cl 335/276, 335/128, 335/297 [51] Int. Cl. H01f 3/14 [58] Fieldof Search 335/276, 297, 128,

[56] References Cited UNITED STATES PATENTS 3,106,669 10/1963 Zerwic335/297 2,449,086 9/1948 Price 335/128 3,109,904 11/1963 Koertge et a1.335/276 2,176,564 10/1939 Stumpf 335/245 3,265,828 8/1966 Com 335/132 1June 12, 1973 Primary Examiner-Harold Broome Att0rney-C. FrederickLeydig, Richard L. Voit,

Edward W. Osann et a1.

[57] ABSTRACT A bobbin assembly in an electric relay, thebobbin having apair of flanges and with one of the flanges having an associated capwhich at least partially encloses the end of the bobbin and which servesas a seating surface for an iron core, the cap having windows formedtherein to provide access for a staking tool so that the core is heldcaptive within the bobbin prior to assembly in the relay. The outer endof the core carries a shading ring which is held in registered positionby an embossment. The cap is clamped between the core and the frame ofthe relay to provide a magnetic gap thereby to reduce the level ofresidual flux when the relaycoil is de-energized.

4 Claims, 6 Drawing Figures Pmunmumlm 1 sum 2 or z BOBBIN ASSEMBLY FORRELAY It is an object of the present invention to provide a bobbinassembly for a relay which establishes the desired gap in the magneticstructure and which permits preassembly of bobbin, coil and core, allproperly integrated with one another, for handling as a unit duringfinal assembly of the relay.

It is a more specific object to provide a bobbin assembly in which thecore is telescoped endwise into seated position in the hollow of thebobbin and in which the core is staked in place. In one of the aspectsof the invention it is an object to provide a bottoming cap as anintegral part of a molded bobbin in which windows are provided in thecap for access of a staking tool.

Generally stated, it is an object of the invention to provide a moldedbobbin which includes features which facilitate assembly and operationbut which may be molded at substantially the same cost as conventionalbobbins.

Other features and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings which:

FIG. 1 is a cross sectional view of a relay employing the presentinvention.

FIG. 2 is an isometric view of the bobbin used in FIG. 1.

FIG. 3 is an isometric view of the bobbin looking from the oppositedirection and with core and shading ring shown in exploded position.

FIG. 3a is an end view of the bobbin following assembly.

FIG. 4 shows the staking operation.

FIG. 5 is a fragmentary view looking along the line 5-5 in FIG. 4showing the windows and staking positions.

While the invention has been described in connection with a preferredembodiment, it will be understood that we do not intend to be limited tothe particularembodiment shown but intend, on the contrary, to cover thevarious alternative and equivalent constructions included within thespirit and scope of the appended claims.

Turning now to FIGnl there is disclosed a relay having a frame 11 ofmagnetic material which, in the present embodiment, is of U-shapedefining a magnetic seat 12 and having a rockable armature 13 which isarranged opposite the seat. The armature is pivoted at 14 and isrestored by means of a spring 15, a suitable stop, not shown, beingprovided for establishing a normal armature position. While theinvention is not concerned with any particular contact structure, itwill be understood that the armature has an extension or bracket 16 forcontrol of a pair of contacts 17.

Mounted within the relay frame is a bobbin 20 upon which is wound anannular coil 21 and within which is telescoped an iron core 22, the corebeing held in place by a screw 23 which engages one end of it. In thecase of a relay intended for use with alternating current a shading coil24 is provided at the outer end of the core and in a position adjacentthe armature.

In accordance with the present invention the bobbin assembly includes abobbin having a hollow cylindrical portion with integral end flanges,the end flange which is adjacent the frame being provided with anintegral cap which at least partly encloses the hollow of the bobbin,the cap having an internal seating surface for seating the presented endof the iron core and the cap being provided with at least one windowproviding access to the edge of the core so that the edge of the coremay be upset or staked over the flange to hold the core in place withinthe bobbin. Further in accordance v with the invention the oppositeflange is provided with register between the core and bobbin prior tostaking an embossment which registers with the shading ring incident toseating the core in place to insure proper the two together.

Thus, referring to the drawings the bobbin 20 has a cylindrical portion30 having flanges 31, 32. The flange 31 has an integral cap 33 whichextends beyond the flange 31 and which provides an internal seatingsurface 34. The cap includes one or more windows 35 which provide accessto the outer edge 36 of the core. The cap is preferably reinforced withrespect to the flange by means of radial reinforcing ribs 37.

integrally formed on the opposite flange is an embossment 40 which maybe in the form of two spaced protuberances mating with surfaces 41 onthe shading ring 24 which, as will be noted, is of D-shape. The shadingring has a cross piece 42. which is received in a slot 43 formed in theouter end of the core, the elements 42, 43 being so dimensioned as toprovide a press fit. In putting together the bobbin assembly, the core22, with shading ring installed, is inserted into the hollow of thebobbin and rotated until the shading ring registers with the embossment.The assembly is then placed, inverted, upon a suitable anvil as shown inFIG. 4 and a staking tool, indicated at T, is inserted through one ormore of the windows 35. The staking tool is planted just inside of theedge 36 of the core and in a staking position indicated at 46. Theresulting upsetting of the soft iron of the core over the adjacent edgeof the flange 31 serves to retain the core securely captive so that thebobbin assembly consisting of bobbin, coil and core may thereafter behandled as a unit incident to final assembly of the relay. Maintainingthe core captive, moreover, insures that the condition of registerbetween the core and its shading ring is maintained until the core isfinally clamped, with respect to the relay frame, in its permanentposition.

In order to insure register between the assembly and the relay frame,one flange of the bobbin is preferably of rectangular outline, with atleast one of the edges thereof mating with the frame as shown in FIG. 1so as to be nonrotatable. All that is necessary to secure the bobbinassembly in place is to drop the assembly into position and to screw inthe screw 23 from the opposite side of the frame. Clearance for thescrew is provided by a central operning 47 in the cap which registerswith an aligned opening provided in the seating surface 12 of the frame.Turning the screw tight clamps the core in the direction of the magneticseating surface 12 with the thickness of the cap 33 being interposedbetween the two members. This thickness, which may be on the order of0.020 inch in a practical case, provides a magnetic gap which addssufficient reluctance to the magnetic loop circuit including framearmature and core so that residual magnetism, when the coil isde-energized, is reduced to a minimum resulting in prompt freeing of thearmature to move to its normal retracted position (FIG. I). Since thebobbin thus provides its own mag netic gap, the relay characteristicsare accurately predetermined to provide a high degree of reliability.The present relay is to be contrasted with prior relays which havesometimes employed a separate nonmagentic washer and which have involvedthe risk that the washer may be inadvertently omitted from theconstruction or that a washer of improper thickness might be used. Thisis, indeed, a difflcult matter to check since any such washer is hiddenbetween the bobbin and the frame, and is relatively thin, making itspresence or absence difficult to check.

In addition to the advantages of the present structure in the magneticcircuit, the assembly provides a high degree of convenience and economyin manufacture since the wound bobbin and core may be preassembled on aproduction line basis, with the only subsequent operation being theaddition of the armature and its spring and the screwing of the bobbinassembly into place. Not only is the number of parts which need behandled in the final assembly operation minimized but standard bobbinassemblies may be produced whtich are usable in different models andstyles of relays, for example, relays having different contactconfiguratrons.

Because the the simplicity of the integral cap and the small amount ofadditional material required, improved bobbins may be molded at a costwhich is, as a practical matter, no greater than the cost of moldingbobbins which do not have the improved features.

.In the above discussion emphasis has been placed upon a preferred formof the present invention in which the cap is extended axially beyond theadjacent flange, being supported with respect to the latter by thereinforcing ribs 37. It will be apparent to one skilled in the art that,if desired, the reinforcing ribs may be omitted and the space around thecap may be filled in resulting in a flange of greater thickness. If thisis done, then the upsetting of the metal of the core will not, strictlyspeaking, the over the end of the flange but will be over a referencesurface such as that indicated at 50 (FIG. 4) which is provided withinthe flange. Such alternative is obviously included within the scope ofthe present invention and the surface 50 may, in such event, beconsidered the end of the flange.

The bobbin may be molded of any plastic having suitable mechanicalcharacteristics, nylon and delrin each providingbobbins of high quality,but less expensive plastics may be used, if desired, within the scope ofthe invention. I

The term screw means as used herein is intended to be a general term tocover a threaded member engaged with, or presented by, the core for thepurpose of clamping the core endwise against the frame.

What I claim is:

1. In an electric relay construction the combination comprising amagnetic frame providing a seat and a rockable armature opposed to theseat, a plastic bobbin having a hollow cylindrical portion and integralend flanges and wound with an annular coil, a cylindrical iron coretelescoped into the bobbin, one flange 'of the bobbin "having anintegral cap for bottomed engagement of the inserted end of the core,and screw means penetrating the frame and the'c'ap for clamping the coreagainst the seat onthe frame with the cap interposed between the twoproviding a magnetic gap thereby to avoid residual magnetism for freeingof the armature promptly when the coil is de-energized.

2. In an ACrelay construction the combination comprising a rectangularmagnetic frame providing a seat and a rockablearmature opposed to theseat, a bobbin of molded plastic material having a hollow cylindricalportion and integral end flanges and wound with an annular coil, theflanges being of rectangular shape dimensioned to fit in the frame, oneof the flanges having an integral cap at least partially enclosing oneend of the bobbin and the other flange having an integral embossmentthereon, a cylindrical iron core dimensioned to telescope into thebobbin and having a shading coil at its outer end for registering withthe embossment, and screw means projecting through the seat and throughthe cap for engagement with the iron core for clamping the iron core tothe seat with the cap interposed between for reduction of residualmagnetism when the coil is de-energized.

3. In an electric relay consruction a magneticframe providing a seat andhaving a rockable armature opposed to the seat, a bobbin and coreassembly, said bobin and core assembly including a bobbin made ofplastic material having a hollow cylindrical portion and integral endflanges and wound with an annular coil, one of the end flanges having anintegral cap which at least partially encloses one end of the bobbin,the bobbin assembly including a cylindrical iron core telescoped intothe bobbin and in bottomed seating engagement with the cap, the caphaving at least one window formed therein exposing the edge of the coreto provide access thereto, the exposed edge of the core being peenedover the adjacent flange for holding the core seated in the bobbin untilthe bobbin assembly is secured in the frame, and screw means at theseated end of the core and projecting through the cap and the frame forclamping the core against the seat with the cap interposed between forreduction of residual magnetism when the coil is de-energized.

4. As an article of manufacture, a bobbin assembly for an AC relay, thebobbin assembly including a bobbin of molded plastic material having ahollow cylindrical portion and integral end flanges and wound with anannular coil, one of the end flanges having an embossment and the otherend flange having an integral cap which at least partially encloses thehollow of the bobbin at one end to define an internal seating surface,an iron core having a shading ring at its outer end extending laterallytherefrom for registering engagement with the embossiment and screwmeans at its inner end, the seating surface within the cap being axiallyspaced from the end of the adjacent flange and the core being sodimensioned that its inner end extends into the cap and slightly beyondthe adjacent flange, the extending portion being peened over theadjacent flange thereby to maintain the core in assembled positionwithin the bobbin for subsequent handling of the assembly as an integralunit, the cap having at least one window therein providing access for apeening tool to the region of the jointbetween the end of the core andthe adjacent flange as well as access to the screw means.

1. In an electric relay construction the combination comprising amagnetic frame providing a seat and a rockable armature opposed to theseat, a plastic bobbin having a hollow cylindrical portion and integralend flanges and wound with an annular coil, a cylindrical iron coretelescoped into the bobbin, one flange of the bobbin having an integralcap for bottomed engagement of the inserted end of the core, and screwmeans penetrating the frame and the cap for clamping the core againstthe seat on the frame with the cap interposed between the two providinga magnetic gap thereby to avoid residual magnetism for freeing of thearmature promptly when the coil is de-energized.
 2. In an AC relayconstruction the combination comprising a rectangular magnetic frameproviding a seat and a rockable armature opposed to the seat, a bobbinof molded plastic material having a hollow cylindrical portion andintegral end flanges and wound with an annular coil, the flanges beingof rectangular shape dimensioned to fit in the frame, one of the flangeshaving an integral cap at least partially enclosing one end of thebobbin and the other flange having an integral embossment thereon, acylindrical iron core dimensioned to telescope into the bobbin andhaving a shading coil at its outer end for registering with theembossment, and screw means projecting through the seat and through thecaP for engagement with the iron core for clamping the iron core to theseat with the cap interposed between for reduction of residual magnetismwhen the coil is de-energized.
 3. In an electric relay consruction amagnetic frame providing a seat and having a rockable armature opposedto the seat, a bobbin and core assembly, said bobin and core assemblyincluding a bobbin made of plastic material having a hollow cylindricalportion and integral end flanges and wound with an annular coil, one ofthe end flanges having an integral cap which at least partially enclosesone end of the bobbin, the bobbin assembly including a cylindrical ironcore telescoped into the bobbin and in bottomed seating engagement withthe cap, the cap having at least one window formed therein exposing theedge of the core to provide access thereto, the exposed edge of the corebeing peened over the adjacent flange for holding the core seated in thebobbin until the bobbin assembly is secured in the frame, and screwmeans at the seated end of the core and projecting through the cap andthe frame for clamping the core against the seat with the cap interposedbetween for reduction of residual magnetism when the coil isde-energized.
 4. As an article of manufacture, a bobbin assembly for anAC relay, the bobbin assembly including a bobbin of molded plasticmaterial having a hollow cylindrical portion and integral end flangesand wound with an annular coil, one of the end flanges having anembossment and the other end flange having an integral cap which atleast partially encloses the hollow of the bobbin at one end to definean internal seating surface, an iron core having a shading ring at itsouter end extending laterally therefrom for registering engagement withthe embossiment and screw means at its inner end, the seating surfacewithin the cap being axially spaced from the end of the adjacent flangeand the core being so dimensioned that its inner end extends into thecap and slightly beyond the adjacent flange, the extending portion beingpeened over the adjacent flange thereby to maintain the core inassembled position within the bobbin for subsequent handling of theassembly as an integral unit, the cap having at least one window thereinproviding access for a peening tool to the region of the joint betweenthe end of the core and the adjacent flange as well as access to thescrew means.